Basic arch for reverberatory furnace



March 22, 1960 HUTTER 2,929,343

BASIC ARCH FOR REVERBERATORY FURNACE Filed Oct. 28, 1954 2 Sheets-Sheet1 Fig. 1 if nited States Patent O i 2,929,343 BASIC Anon FonREVERBERATORY FURNACE Luis Hutter, Munich, Germany, assignor to GeneralRefractories Company, Philadelphia, Pa.

Application October 28, 1954, Serial No. 465,402

Claims priority, application Austria October 30, 1953 2 Claims. (Cl.110-99) The present invention relates to basic arches or roofs forreverberatory furnaces especially open hearth steel furnaces.

The invention aims at reducing to a minimum the stress in the arch whicharises from the properties of basic brick; and especially from theirgreat tendency to expand during operation.

According to the invention this advantage is achieved by producing anarch composed of rib-forming brick and groove-forming brick between therib-forming brick, with the rib-forming brick both suspended andsupported and with the groove-forming brick suspended, suitably from therib-forming brick. Thus the groove-forming brick are indirectlysuspended by means of the rib-forming brick, since the groove-forming orintermediate brick are suspended by the rib-forming brick or by theirsuspension.

There are numerous ways in which the suspension of the groove-formingbrick may be accomplished. In a preferred embodiment the suspensiondevices, suitably suspension sheets, are arranged on the lateral facesof the brick and extend beyond the cold front end. In anotheradvantageous form the suspension of the grooveforming or intermediatebrick consists of anchors intruding into recesses in the cold front endsof the grooveforming brick. In this case the groove-forming orintermediate brick are suitably anchored to girders or supporting barswhich extend in the longitudinal direction of the arch and are supportedby the rib-forming brick.

In an arch in accordance with the invention, especially where therib-forming brick have to support the groove-forming or intermediatebrick, the rib-forming brick require a greater mechanical strength. Itis therefore advisable to use for the rib-forming brick chromemagnesiabrick containing more than 55 percent of chrome by weight, since thesehave a high refractornessunder-load and a great resistance totemperature changes. These brick are preferably used tired.

For the groove-forming or intermediate brick, magnesia-chrome brick aresuitably used, desirably containing more than 55 percent magnesia byweight, and these are preferably laid in the form of unred brick andsubjected to firing temperature inthe furnace during use.

In accordance with technical usage, the term chromemagnesia brick isintended to refer to brick produced from mixtures of chrome ore andsintered or fused magnesia containing chrome ore in a predominantproportion by Weight. The term magnesia-chrome brick is intended todenote brick produced from mixtures of the same raw materials containingmagnesia in the predominant proportion by weight. For the groove-formingor intermediatte brick metal encased brick commonly referred to as steelclad brick are advantageously used.

The ribs in the rib arch serve to strengthen and reenforce the arch. Ifthe groove-forming brick are not suspended, there is often a tendencyfor large parts of the groove-like sections of the arch to cave inbefore the back brick come into use, where an extra layer of back2,929,343 Patented Mar. 22, 1960 brick is applied on the cold ends ofthe groove brick. Although in the case of the suspended groove brick,backing of the brick is not possible, nevertheless by suspending thegroove-forming brick it is possible to extend the service life of therib arches considerably without even needing backing brick on the groovebrick. It has been found that there is no danger of prematuredestruction of the suspension. Thus the arch in accordance with theinvention combines the advantages of the roof reinforced by ribs andthose of suspension to al1 of the brick.

In order to enable the invention to be more readily understood,reference is made to the accompanying drawings which illustratediagrammatically and by way of example two embodiments of the invention.

Figure l is a perspective view of the roof of the invention partly inlongitudinal vertical section.

Figure 2 is an enlarged longitudinal vertical section of Figure 1.

Figure 3 is a perspective view of a further embodiment partly inlongitudinal vertical section.

Figure 4 is an enlarged longitudinal vertical section of Figure 3.

The arch shown in Figures 1 and 2 consists of pairs of rib-forming brick1 of greater length and pairs of groove-forming or intermediate brick 2of shorter length. The rib-forming brick have smaller cold ends 3 whichenlarge at a shoulder or step 4 to the full width on each side. On topof the row of rib-forming brick extend supports 6 from which therib-forming brick are suspended by wire loops 7 which pass throughtransverse holes 8 arranged in the smaller ends 3 of the rib-formingbrick. These holes if desired are lined with short seotions of metallicpipe.

The groove-forming or intermediate brick are suspended by means ofsuspension Sheets 10 suitably of steel which have openings through whichthe supporting bars 11 pass. The bars extend in the longitudinaldirection of the arch and rest on the shoulders 4 of the rib-formingbrick and are thus supported from the ribforming brick. The suspensionsheets are inserted into the joints between the rows of groove-formingbrick and extend beyond the cold end of the groove-forming brick toprovide ears which carry the holes through which the supporting bars 11extend.

The rib-forming brick 1 which not only form the supporting andstrengthening ribs of the arch but which also support the groove-formingor intermediate brick 2 preferably are fired chrome-magnesia brick.

The groove-forming or intermediate brick 2 are prefably magnesia-chromebrick which are desirably laid in the uniired state with the insertionof sheets or wire gauze of oxidizable metal such as steel along thelateral surface. These spacer plates may be the sheets 10 of Figures 1and 2, in which case they are desirably joined to the bricks byco-molding. The spacer plates melt at the hot end when the furnace isheated up for the first time to operating temperature and oxdize tocausethe brick to be fritted together. The principles o-f the inventionare applicable whether or not the groove-forming brick 2 are metalencased brick.

The arch shown in Figures 3 and 4 differs from that described inreference to Figures l and 2 only in regard to the means for suspensionof the groove forming brick 2. At the cold end the groove-forming brickare provided with insertion pockets 15 which serve for anchoring heads16 of`T-shaped suspension irons or hangers 17. The legs of thesesuspension arms have holes 13 through which the supporting bars 11extend. In the embodiment shown, the insertion pockets 15 are formed byU-shaped metal insertions 19, which have the legs of the U embodied inthe brick material by co-molding.

@ne or the advantages of the arch of the present invention is thatit hasa relatively long service life. Thechrorne-magnesia rib-forming brickimpart to the arch great refractoriness-under-load and resistance totemperature change while the magnesia-chrome grooveforming brick impartincreased resistance especially to chemical attack such as infiltrationof iron oxides and bursting. By arranging the ribs at longer or shorterdistances from each other, and therefore by using a greater or` smallernumber of groove-forming or intermediate brick, it is possible to adaptthe above described arch to the most diver-se plant conditions.

In view of my invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled i-n'the art, to obtain vall or partof the benefits of myinventionwithout copying the structure shown, and '1, therefore, claimall such insofar as they fall within the reasonable spirit and scope ofmy claims.

HavingV thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A basic arch roof for reverberatoryl furnaces, such as open hearthfurnaces, comprising two kinds of basicV krefractory bricks of differentsizes, which kind of bricks on the one hand are rib-formingchrome-magnesia bricks consisting. ofV at least 55% chrome refractoryarranged in transverse rows spaced longitudinally of the roof, and onthe other hand are groove-forming magnesia-chrome bricks consisting ofat least 55% magnesia arranged in transverse rows spaced longitudinallyof the roof and disposed in alternating relation to said rows ofribforming bricks, said transverse rows having an arch configuration inthe roof, the groove-forming bricks further being in rows extendinglongitudinally of the roof between a corresponding pair of saidtransverse rows of the rib-forming bricks with at least twogroove-forming bricks in each longitudinal row, said rib-forming bricksbeing longer than said groove-forming bricks and extending upward beyondsaid groove-forming bricks on the cold sideof the roof, and affordingshouldersA above 4; said groove-forming bricks, support means extendingalong the transverse rows of rib-forming bricks on the cold side of theroof and suspension means interconnecting said support means andrib-forming bricks, and said longitudinal rows of groove-forming bricksbeing in separately hung assemblies including supporting bars over saidlongitudinal rows on the cold side of the roof and hangers forV theindividualbricks in said longitudinal rows suspending the bricks fromthe supporting bars, said bars extending between the adjacent transverserows of rib-forming bricks longitudinally of the roof and havingopposite ends resting directly on the shoulders of said rib-formingbricks, whereby the groove-forming bricks are partially supported by therib-forming bricks and partially by each other.

2. A basic roof' of claim l, wherein said chrome-magnesia bricks areburned bricks and said magnesia-chrome bricks are unburned bricks.

References Cited in the tile of' this patent Y UNITED STATES PATENTS1,534,472 Sten/,ens` .Y s Apr. 21, 1925 1,738,527/ Dobiec Dec. 10, 19291,845,968 Heuer Feb. 16, 1932 '2,187,669 Stewart. v Jan. 16, 19402,216,813, Goldschmidtc Oct. 8, 1940 2,465,170 RochowY Mar. 22, 19492,529,607 l s L Y 1950 2,577,428 Mohr Dec. 4, 1951 2,606,017 Longenecker1952 2,652,793: Heuer Sept. 22, 1953 2,670,698 Poth Mar 2, 19542,698,588' DavisI Ian 4, 1955l 2,699,741 Bowman Jan. 18, 1955y2,781,006. Heuer Feb. 12, 1957 FOREIGN, PATENTS 807,010 France Oct. 5,1936 844,656; Germany --,-17,,- July 24, 1952

